WordPress “Art Direction” Plugin, from Automattician Noel Jackson. Basically allows you to do what Jason Santa Maria does for his blog without all the custom code and template hacking, just a simple plugin.
After being frustrated with
mod_rewrite mojo, I wrote a quickie no-www plugin for WordPress that redirects people to the non-www version of your URLs, in the spirit of no-www.org. Update: This is now built into WordPress through the “canonical URLs” feature, just go to the General Settings page and remove “www” from the blog and WP URLs.